The present invention is directed to optical bar code scanning devices and more particularly to a portable bar code scanning device in which a bar code label is moved under the stationary scanning head during a merchandise checkout operation.
In present-day merchandising point-of-sale operations, data pertaining to the purchase of a merchandise item is obtained by reading data encoded indicia such as a bar code label printed on or attached to the merchandise item. In order to standardize the bar codes used in various point-of-sale checkout systems, the grocery industry has adopted a uniform product code (UPC) which is in the form of a bar code. Reading systems which have been constructed to read this bar code include hand-held wands which are moved across the bar code and stationary optical scanning systems normally located within the cabinet structure of a checkout counter in which the bar code is read when a purchased merchandise item is moved across a window constituting the scanning area of the counter, which movement is part of the process for loading the item in a baggage cart. The hand-held wands or scanners emit a single scan line which is directed over the bar code by the operator while the stationary optical reader systems produce a multiline scan pattern through which the bar code label is moved, enabling a higher throughput of reading processed bar code labels to occur over that of the hand-held scanner. There has arisen a need for a portable scanning system which does not require the higher throughput of the stationary reader and yet is more convenient to use than hand-held scanning systems.
The background art known to the Applicants at the time of the filing of this application includes: U.S. Pat. No. 4,369,361 which discloses a portable stand-alone desk-top laser scanning workstation including a laser scanning head mounted above a support base facing the operator in which objects bearing bar code symbols to be scanned are passed underneath the head, and U.S. Pat. No. 4,766,297 which discloses a support member for supporting a portable hand-held scanning device in which the fixture includes structure for sensing the presence of an object between the head portion and the base portion of the fixture and for automatically initiating a reading of bar code symbols by the portable hand-held scanning device each time the sensing structure senses the presence of an object.